# Enhanced Spin Conductance of a Thin-Film Insulating Antiferromagnet

## TL;DR

This paper studies how spin conductance in an antiferromagnetic insulator dramatically increases near the spin-flop transition, revealing potential for tunable spin current applications.

## Contribution

It provides a theoretical analysis of spin transport in antiferromagnets near phase transitions, highlighting the divergence of spin conductance at the spin-flop transition.

## Key findings

- Spin conductance diverges near the spin-flop transition.
- Spin Seebeck coefficient remains finite at the transition.
- Large tunability of spin currents is achievable through magnetic field control.

## Abstract

We investigate spin transport by thermally excited spin waves in an antiferromagnetic insulator. Starting from a stochastic Landau-Lifshitz-Gilbert phenomenology, we obtain the out-of-equilibrium spin-wave properties. In linear response to spin biasing and a temperature gradient, we compute the spin transport through a normal metal$|$antiferromagnet$|$normal metal heterostructure. We show that the spin conductance diverges as one approaches the spin-flop transition; this enhancement of the conductance should be readily observable by sweeping the magnetic field across the spin-flop transition. The results from such experiments may, on the one hand, enhance our understanding of spin transport near a phase transition, and on the other be useful for applications that require a large degree of tunability of spin currents. In contrast, the spin Seebeck coefficient does not diverge at the spin-flop transition. Furthermore, the spin Seebeck coefficient is finite even at zero magnetic field, provided that the normal metal contacts break the symmetry between the antiferromagnetic sublattices.